Validation of the LupusPRO in Chinese Patients From Hong Kong With Systemic Lupus Erythematosus

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1 Arthritis Care & Research Vol. 67, No. 2, February 2015, pp DOI /acr , American College of Rheumatology ORIGINAL ARTICLE Validation of the LupusPRO in Chinese Patients From Hong Kong With Systemic Lupus Erythematosus CHI CHIU MOK, 1 MARK KOSINSKI, 2 LING YIN HO, 1 KAR LI CHAN, 1 AND MEENAKSHI JOLLY 3 Objective. LupusPRO is a disease-targeted, patient-reported outcome (PRO) measure that was developed and validated for assessment of quality of life in US patients with systemic lupus erythematosus (SLE). We present results of adapting the LupusPRO into Chinese and testing its psychometric properties in Chinese patients with SLE. Methods. LupusPRO was translated into traditional Chinese, followed by pretesting among native Cantonese Chinese speakers. The translation version was revised based on the feedback obtained. The Chinese language LupusPRO tool was administered along with a generic PRO tool (the Short Form 36 health survey [SF-36]) to ethnic Chinese SLE patients. At the same time, demographic information, clinical data, disease activity (Safety of Estrogens in Lupus Erythematosus National Assessment [SELENA] version of the Systemic Lupus Erythematosus Disease Activity Index [SLEDAI]), and damage (Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index [SDI]) were obtained. We performed confirmatory factor analysis of the Chinese LupusPRO and evaluated internal consistency reliability, as well as convergent and criterion validity. Results. Among the 463 SLE patients (95% women) with a mean SD age of years, the mean SD physician global assessment score was , the mean SD SELENA-SLEDAI score was , and the mean SD SDI score was Results of factor analysis conformed to the original LupusPRO model with only minor modifications. The reliability of the LupusPRO domains ranged from LupusPRO domains had correlations as expected with the corresponding SF-36 domains. A significant but weak correlation with disease activity was noted for criterion validity as expected. Conclusion. The Chinese language LupusPRO has fair psychometric properties and may be used in SLE clinical trials. INTRODUCTION 1 Chi Chiu Mok, MD, FRCP, Ling Yin Ho, MB, FRCP, Kar Li Chan, MB, FRCP: Tuen Mun Hospital, Hong Kong, China; 2 Mark Kosinski, MA: QualityMetric Incorporated, Lincoln, Rhode Island; 3 Meenakshi Jolly, MD, MS: Rush University Medical Center, Chicago, Illinois. Dr. Mok has received an honorarium (less than $10,000) from Pfizer. Dr. Jolly has received consulting fees, speaking fees, and/or honoraria (more than $10,000) from GlaxoSmithKline and has received a patent, license, or licensing fee for LupusPRO from MedImmune and Eli Lilly. Address correspondence to Chi Chiu Mok, MD, FRCP, Department of Medicine, Tuen Mun Hospital, Tsing Chung Koon Road, New Territories, Hong Kong, SAR China. E- mail: ccmok2005@yahoo.com. Submitted for publication March 24, 2014; accepted in revised form August 12, Systemic lupus erythematosus (SLE) is a chronic multisystemic autoimmune disease that mainly affects women of the reproductive age. The disease course is unpredictable and interspersed with periods of exacerbations and remissions (1). Although the prognosis of the disease has improved tremendously in the past few decades, further improvement is hindered by many factors that include refractory manifestations and toxicities related to conventional therapies (2). Because of symptoms related to disease activity, treatment-related complications, or accrued damage, the quality of life of patients with SLE is significantly impaired. A number of studies in different ethnic groups have reported poorer quality of life in patients with SLE when compared to healthy subjects (3 5). In a previous longitudinal study involving 155 Chinese SLE patients, we showed that health-related quality of life (HRQOL) was significantly impaired when compared to controls and adjusting for age, sex, education, and poverty (6). Preexisting organ damage was associated with poorer HRQOL, and new damage over 2 years predicted further decline in HRQOL. In another study, it was shown that the quality of life of SLE patients was worse than with some other common chronic diseases (7). The Medical Outcomes Study Short Form 36 (SF-36) has been the most commonly utilized patient-reported outcome (PRO) tool in longitudinal observational studies and randomized controlled therapeutic trials of SLE (8 10). It is well validated but not specific to SLE. Disease-specific 297

2 298 Mok et al Significance & Innovations The LupusPRO is a disease-targeted, patientreported outcome measure that has been validated for assessment of quality of life in US patients with systemic lupus erythematosus (SLE). This study validates the Chinese language LupusPRO in a large cohort of southern Chinese patients with SLE. The Chinese LupusPRO has fair psychometric properties and can be used for clinical trials. questionnaires have been developed with the intention of enhancing the responsiveness and content validity for SLE compared to generic instruments. The LupusPRO is a disease-targeted PRO measure that was developed and validated in the US from SLE patients (11). Unlike other lupus-specific questionnaires, such as the UK LupusQoL (12), it consists of both 8 health-related and 4 non healthrelated domains to enable an understanding of the broader burden of the disease. The LupusPRO has been cross culturally adapted and validated in various countries (Canada, Philippines) and different languages, such as Turkish, Spanish, French, and Filipino (13 16). However, it has not been validated in Chinese. We hereby report the results of cross-cultural adaptation of the LupusPRO into the Chinese language, and testing of its psychometric properties among Chinese patients with SLE. PATIENTS AND METHODS Study population and data collection. Consecutive SLE patients who attended the rheumatology outpatient clinics or were admitted to the medical wards of Tuen Mun Hospital, Hong Kong, China between February and June 2013 were recruited. All patients were ethnic Chinese, with their family origin in the southern part of China and had fulfilled at least 4 of the 1997 American College of Rheumatology classification criteria for SLE (17). Written consent was obtained from all the participants. The study was approved by the Ethics Committee of Tuen Mun Hospital, Hong Kong. Participants were asked to complete the LupusPRO questionnaire along with a generic PRO tool, the SF-36. Demographic and clinical data (clinical manifestations, autoantibodies, and medications within 1 month of study) were obtained. SLE disease activity at the time of questionnaire completion was assessed by the Safety of Estrogens in Lupus Erythematosus National Assessment (SELENA) version of the Systemic Lupus Erythematosus Disease Activity Index (SLEDAI), and organ damage was assessed by the Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index (SDI). Table 1. Characteristics Clinical characteristics of the SLE study population* Value Age, mean SD years Women 442/463 (95.0) ACR criteria Malar rash 227/455 (49.9) Discoid rash 49/454 (10.8) Oro/nasal sores 62/454 (13.7) Photosensitivity 129/454 (28.4) Arthritis 314/457 (68.7) Serositis 93/457 (20.4) Lupus nephritis 236/463 (51.0) Hematologic 355/463 (76.7) ANA 463/463 (100.0) Medications Corticosteroids 184/463 (60.0) Hydroxychloroquine 296/463 (63.9) Azathioprine 179/462 (38.7) Methotrexate 24/463 (5.2) Mycophenolate mofetil 80/463 (17.3) Disease activity Physician global assessment Mean SD Median (IQR) 0.30 (0.40) Total SELENA-SLEDAI score Mean SD Median (IQR) 2.0 (4.0) SELENA-SLEDAI score 4 77/463 (16.6) Damage SDI Mean SD Median (IQR) 0.0 (1.0) SDI 1 (%) 183/463 (39.5) * Values are the number/total number (percentage) unless indicated otherwise. SLE systemic lupus erythematosus; ACR American College of Rheumatology; ANA antinuclear antibody; IQR interquartile range; SELENA-SLEDAI Safety of Estrogens in Lupus Erythematosus National Assessment version of the Systemic Lupus Erythematosus Disease Activity Index; SDI Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index. LupusPRO. The LupusPRO has 2 constructs: HRQOL and non-hrqol. The HRQOL domains are SLE symptoms, cognition, SLE medications, physical health (physical function and role physical), pain-vitality (fatigue, sleep), body image, emotional health (emotional function and role emotional), and procreation (sexual health and reproduction). The non-hrqol domains are desires/ goals, relationship/social support, coping, and satisfaction with medical care. LupusPRO has 43 items (30 for HRQOL construct and 13 for non-hrqol construct) and a 4-week recall period. Each item has 5 options ranging from none of the time to all of the time. The survey completion time ranges from 5 to 7 minutes. Each domain, total HRQOL, and total non-hrqol scores range from 0 to 100, where a higher score denotes better quality of life. The tool has excellent psychometric properties in US patients (11). Translation. The 43-item English LupusPRO was translated by a certified translation company using standard guidelines (18) into traditional Chinese, using forwards and backwards translation methods. Two translators of each language were involved in the process of forwards

3 LupusPRO in Chinese Patients With SLE 299 Table 2. HRQOL among Chinese SLE patients using LupusPRO and SF-36* LupusPRO domains Mean SD Median (IQR) Floor effects, % minimum score of 0 Ceiling effects, % minimum score of 0 Missing responses, % Lupus symptoms (33.3) Cognition (37.5) Lupus medications (37.5) Physical health (25.0) Pain-vitality (35.0) Body image (30.0) Emotional health (37.5) Procreation (25.0) Desires-goals (37.5) Social support (37.5) Coping (25.0) Satisfaction with medical care (43.8) SF-36 domains Physical function (35.0) Role physical (100.0) Bodily pain (43.0) General health (32.0) Viality (30.0) Social function (50.0) Role emotion (100.0) Mental health (28.0) * HRQOL health-related quality of life; SLE systemic lupus erythematosus; SF-36 Medical Outcomes Study Short Form 36; IQR interquartile range. and backwards translations. The backward translation (English version) was reviewed by an author (MJ; the LupusPRO developer) to confirm that the concepts of the LupusPRO items, responses, instructions, and the overall tool remained the same. Feedback was provided to the translation company, and appropriate changes were made when needed to maintain the integrity of the original tool in the translated version. The finalized version was also reviewed carefully by the first author (CCM), a native Chinese (Cantonese) language speaker, and minor changes were made to retain the traditional Chinese language form throughout the survey. The translated tool was pretested among 5 native Cantonese Chinese speakers. Based on the feedback obtained, the translated tool was revised until no issues on feedback from pretesting were noted. The finalized tool was then administered to 463 patients with SLE. Psychometric properties. The Consensus-Based Standards for the Selection of Health Measurement Instrument distinguishes 3 quality domains: reliability, validity, and responsiveness (19). The psychometric properties studied in this paper included reliability and validity. Reliability indicates the degree to which the measurement is free from measurement error. Internal consistency reliability (ICR) reflects the degree of interrelatedness among the items of the same domain. Validity is the degree to which the measure reflects what it is supposed to measure. Construct validity refers to the degree to which the scores of the instrument are consistent with the hypotheses (e.g., with regard to internal relationships, relationships to scores of other instruments, or differences between relevant groups). Hypotheses regarding internal relationships are often tested using confirmatory factor analysis (CFA). Analyses regarding external relationships encompass analyses of convergent, discriminant, criterion, and knowngroups validity. Convergent validity is present if the new instrument scores correlate with other measures of the same construct. Discriminant validity requires lack of correlation with unrelated constructs. Criterion validity refers to the correlation between the new instrument and an external objective reference. Known-groups validity is determined by the ability of the instrument to differentiate between groups that are known to vary in their characteristics, e.g., disease activity. Assessment of SLE activity and damage. Disease activity of SLE was assessed by the SELENA-SLEDAI, a validated instrument that was employed in the SELENA trials (20). SELENA-SLEDAI includes the physician global assessment (PGA) of disease activity (score 0 3). The PGA and the total SLEDAI score were used in this study. Organ damage was assessed by the SDI (21). Damage (after SLE diagnosis) must be present for 6 months before it is scored, irrespective of the cause, and be irreversible. Statistical analyses. The conceptual framework (hypothesized item to scale relationships) of the LupusPRO was evaluated using CFA appropriate for categorical data. CFA was conducted with the LupusPRO item responses using a robust weighted least squares estimator. Items were considered to have strong loading if the item factor loading was The goodness of fit of the hypothesized

4 300 Mok et al Table 3. Confirmatory fit analysis for LupusPRO-Chinese* Factor loadings Lupus symptoms Item Item Item Cognition Item Item Lupus medications Item Item Procreation Item Item Physical health Item Item Item Item Item Pain-vitality Item Item Item Item Item Emotional health Item Item Item Item Item Item Body image Item Item Item Item Item Desires-goals Item Item Item Item Social support Item Item Coping Item Item Item Satisfaction scale Item Item Item Item Model fit statistics Chi-square test CFI RMSEA * CFI comparative fit index; RMSEA root mean square error of approximation. Residual correlation between item 5 and item Residual correlation between item 2 and item item to scale relationships was evaluated with the comparative fit index (CFI) and the root mean square error of approximation (RMSEA). The CFI quantifies the amount of difference between the examined model and the independence model, while the RMSEA quantifies the difference to the fully saturated model. General recommendations are that acceptable fit requires CFA 0.95 (22,23) and RMSEA The ICR for each domain was evaluated using Cronbach s alpha. In some cases, the CFA revealed correlated residuals (local item dependence [24,25]), which may inflate the ICR. We adjusted for local dependence in ICR analyses by forming testlets for the locally dependent items (25). We hypothesized a moderate correlation between corresponding domains (physical health, emotional health, and fatigue-pain) of the LupusPRO and the SF-36 (physical function, role physical, mental health, role emotional, bodily pain, and vitality) to establish convergent validity. Correlation between corresponding LupusPRO and SF-36 domains was assessed using Spearman s correlation coefficient for convergent validity. Discriminant validity of LupusPRO domains using correlational analysis against nonrelated domains of the SF-36 was assessed. Criterion validity for the lupus symptoms domain was performed against disease activity assessments (SELENA-SLEDAI and PGA). Criterion validity was judged using the correlation between LupusPRO domains and physician-based measures of disease activity and damage (SELENA-SLEDAI descriptors and total scores, SDI total scores). A weak correlation between LupusPRO and SLE disease activity was hypothesized due to a priori and unique PRO information captured by the tool. Correlations were classified as strong (r 0.5), moderate (0.3 r 0.5), weak (0.1 r 0.3), or absent (r 0.1). Known-group validity was judged against patient-reported health status (SF-36, item 1) and disease status (SELENA- SLEDAI and SDI). Analysis of variance, with assumption of unequal variance between groups, was used to compare LupusPRO domain scores stratified by known groups. All reported P values were 2-tailed. RESULTS A total of 463 Chinese patients with SLE were studied (95% women). The mean SD age of the patients was years and the mean SD SLE duration was years. Table 1 shows the cumulative clinical manifestations of the patients studied. At the time of questionnaire completion, the mean SD PGA score was and the median score was 0.3 (interquartile range [IQR] 0.4). The mean SD SELENA-SLEDAI score was , median 2.0 (IQR 4.0). The mean SD SDI score was , median 0.0 (IQR 1.0). Seventy-seven patients (16.6%) had a SELENA-SLEDAI score of 4, while 183 (39.5%) had a SDI score of 1. Sixty percent of the patients were on prednisolone and 64% of patients were receiving hydroxychloroquine (Table 1). Summary

5 LupusPRO in Chinese Patients With SLE 301 Table 4. Reliability and validity of LupusPRO* LupusPRO domain Internal consistency reliability Convergent validity Criterion validity Rho P Rho P Lupus symptoms 0.62 PGA Total SLEDAI SLEDAI-rash SLEDAI-alopecia SLEDAI-mucosal ulcers Cognition 0.84 Lupus medications 0.79 PGA Physical health 0.82 Physical function Role physical SLEDAI-arthritis SDI Pain-vitality 0.91 Bodily pain Vitality SLEDAI-arthritis SLEDAI-myositis SLEDAI-rash SLEDAI-alopecia SLEDAI-mucosal SDI Body image 0.94 SLEDAI-rash SDI Emotional health 0.88 Mental health Role emotional SLEDAI-rash Procreation 0.87 Desires-goals 0.75 Social support 0.81 Coping 0.60 Satisfaction with treatment 0.88 HRQOL PCS MCS PGA Total SLEDAI Non-HRQOL PCS MCS * PGA physician global assessment; SLEDAI Systemic Lupus Erythematosus Disease Activity Index; SDI Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index; HRQOL health-related quality of life; PCS physical component scale; MCS mental component scale. Adjusted for locally dependent items. LupusPRO and SF-36 domain scores are shown in Table 2, along with floor and ceiling effects for both the tools. To obtain satisfactory model fit in the CFA (CFI 0.955, RMSEA 0.080), 2 minor model modifications were necessary: specification of residual correlations between items 5 and 6 in the emotional health scale and between items 2 and 3 in the desires/goals scale (Table 3). The model fit statistics on CFA (Table 4) were in the acceptable range (CFI 0.90, TLI 0.90, and RMSEA 0.10). All item loadings were strong, except for 1 coping item (item 3), which had a loading of The ICR of the LupusPRO domains ranged from (Table 4). LupusPRO domains showed convergent validity against the corresponding SF-36 domains (Table 4). Divergent validity of LupusPRO domains was also observed, i.e., noncorresponding domains of LupusPRO with

6 302 Mok et al Table 5. Known-groups validity using patients self-report on current health status on the SF-36 (item 1)* Excellent, n 11 Very good, n 68 Good, n 122 Fair, n 212 Poor, n 46 P Lupus symptoms (16.7) 83.3 (22.9) 83.3 (25.0) 75.0 (33.3) 75.0 (33.3) Cognition (12.5) 75.0 (37.5) 75.0 (37.5) 62.5 (25.0) 43.8 (37.5) Lupus medications (0.0) 87.5 (25.0) 75.0 (37.5) 75.0 (37.5) 50.0 (50.0) Procreation (0.0) (25.0) (25.0) (25.0) (12.5) Physical health (0.0) (10.0) 95.0 (20.0) 90.0 (30.0) 80.0 (45.0) Pain-vitality (5.0) 90.0 (23.8) 80.0 (35.0) 70.0 (40.0) 47.5 (41.3) Emotional health (0.0) 79.2 (25.0) 75.0 (33.3) 58.3 (33.3) 41.7 (34.4) Body image (0.0) (10.0) 95.0 (20.0) 82.5 (35.0) 75.0 (42.5) Desires-goals 93.8 (50.0) 93.8 (25.0) 81.3 (37.5) 75.0 (31.3) 68.8 (39.1) Social support 87.5 (50.0) 75.0 (34.5) 75.0 (50.0) 62.5 (37.5) 50.0 (28.1) Coping 66.7 (50.0) 62.5 (25.0) 54.2 (33.3) 50.0 (25.0) 50.0 (33.3) 0.03 Satisfaction with care 43.8 (62.5) 53.1 (50.0) 43.8 (43.8) 43.8 (37.5) 50.0 (34.4) 0.46 * Values are the median (interquartile range) unless indicated otherwise. SF-36 Short Form 36 health survey. Unable to compute. SF-36 did not show a significant correlation. For example correlation between the LupusPRO procreation domain with the SF-36 social function domain was 0.03 (P 0.49). Known-groups validity evaluated against the first item of SF-36 for current health status showed acceptable results (Table 5). Similar findings were also noted for disease activity and damage categories in most domains (data not shown). DISCUSSION PROs constitute 2 of the 4 core outcome measures recommended for use in SLE by the Outcome Measures in Rheumatology trial (26), i.e., quality of life and adverse effects of treatment. Evaluation of the adverse effects of SLE or its treatment is important not only for patients direct medical care, but also to gauge the indirect effects the disease has on their daily lives. For example, effects such as fatigue, an inability to plan, and reduced physical health have been significantly associated with impaired productivity (26). Patients whose careers were affected by SLE had worse HRQOL, more fatigue, and worse productivity than patients whose careers were not affected (27). Therefore, the indirect and direct physical, emotional, social, and financial cost of SLE to the patient, family, community, and health care delivery system needs to also be considered, while estimating the overall burden of the disease. It is well known that PROs correlate poorly with disease activity assessments (28). It is important to note that the lack or poor correlation is primarily a result of PRO and disease activity assessments being 2 completely different constructs and processes. More importantly, each provides useful yet unique information that may be used to improve patient medical care and overall health outcomes. In some studies, generic PROs have been used to better understand the impact of SLE on patients daily activities, health status, and quality of life. There are significant advantages to using generic PROs. However, there are reports of the SF-36 not being responsive to changes over time toward changes in disease activity (29). Changes noted in this study were limited to the fatigue domain over time, and these were aligned to changes in fibromyalgia rather than SLE activity (29). Similar observations have been published about another generic tool (EuroQol 5-domain measure) and an index (Short Form 36 health survey) despite their being validated for use in SLE (30). The search for a pertinent tool to measure (PRO) in SLE has led to some groundbreaking work and has yielded recognition of well-defined themes that are relevant and/or specific to SLE (11,12,31). Quality of life in SLE is adversely affected both directly and indirectly from SLE itself or its treatment. Although evaluation of direct effects of the disease are more relevant from the care provider viewpoint, it is important to also assess the indirect effects of the disease from the viewpoints of the patient, their family, third-party payers, resource allocation, and health policy makers. Of the currently available disease-targeted PRO tools for SLE (32), LupusPRO is the only PRO tool that allows a comprehensive evaluation of both the aspects. The tool has been found to have fair psychometric properties (including measurement equivalence) in different languages and countries (11,13 16,33) and is responsive to changes in disease activity (34). The Chinese-translated version demonstrated fair psychometric properties among SLE patients in our study. Limitations of the study include recruitment from a single center, which may limit generalizability of results. We also did not have data on education and marital status, as these are known to be associated directly with health behaviors and quality of life. The mean disease activity was not high in our study group, and only 16% of our patients had active disease. Lupus symptoms and coping domains had an ICR of 0.7, but One reason for this could be that each of these 2 domains includes only 3 items each. Secondly, sociocultural beliefs and health behaviors may affect openly endorsing patients coping behaviors (spiritual/religious item) and lupus symptoms (especially loss of hair item). This needs to be further studied. Ceiling effects noted were modestly high for some domains, but similar findings were noted for the SF-36 tool. Some of the

7 LupusPRO in Chinese Patients With SLE 303 domains were expected to have ceiling effects (e.g., procreation, body image, satisfaction with care, coping, and social support) due to milder disease, age (procreation), cultural beliefs, and social desirability bias. One of the possible reasons for the item on coping (related to spirituality/religion) not functioning well on confirmatory factor analysis may be due to differences in cultural or religious beliefs. Overall, the CFA indicated a good fit for the LupusPRO items to the hypothesized domains. A major strength of our study lies in its study size and the evaluation of the disease activity, damage, and studyform administrations by the same personnel, thereby removing interobserver variability. We concluded that the Chinese language LupusPRO has fair psychometric properties, and may be used in SLE clinical trials. Longitudinal observation studies on the sensitivity of the LupusPRO to change over time in our cohort of SLE patients are underway. AUTHOR CONTRIBUTIONS All authors were involved in drafting the article or revising it critically for important intellectual content, and all authors approved the final version to be submitted for publication. Dr. Mok had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis. Study conception and design. Mok, Ho, Chan, Jolly. Acquisition of data. Mok, Ho, Chan. Analysis and interpretation of data. Mok, Kosinski, Ho, Chan, Jolly. REFERENCES 1. Mok CC. Emerging biological therapies for systemic lupus erythematosus. Expert Opin Emerg Drugs 2014;19: Mok CC. Epidemiology and survival of systemic lupus erythematosus in Hong Kong Chinese. Lupus 2011;20: Doria A, Rinaldi S, Ermani M, Salaffi F, Iaccarino L, Ghirardello A, et al. Health-related quality of life in Italian patients with systemic lupus erythematosus. II: role of clinical, immunological and psychological determinants. Rheumatology (Oxford) 2004;43: Rinaldi S, Doria A, Salaffi F, Ermani M, Iaccarino L, Ghirardello A, et al. Health-related quality of life in Italian patients with systemic lupus erythematosus. I: relationship between physical and mental dimension and impact of age. Rheumatology (Oxford) 2004;43: Ruperto N, Buratti S, Duarte-Salazar C, Pistorio A, Reiff A, Bernstein B, et al. Health-related quality of life in juvenileonset systemic lupus erythematosus and its relationship to disease activity and damage. Arthritis Rheum 2004;51: Mok CC, Ho LY, Cheung MY, Yu KL, To CH. Effect of disease activity and damage on quality of life in patients with systemic lupus erythematosus: a 2-year prospective study. Scand J Rheumatol 2009;38: Jolly M. How does quality of life of patients with systemic lupus erythematosus compare with that of other common chronic illnesses? J Rheumatol 2005;32: Strand V, Levy RA, Cervera R, Petri MA, Birch H, Freimuth WW, et al, for the BLISS-52 and -76 Study Groups. Improvements in health-related quality of life with belimumab, a B-lymphocyte stimulator-specific inhibitor, in patients with autoantibody-positive systemic lupus erythematosus from the randomised controlled BLISS trials. Ann Rheum Dis 2014;73: Alarcon GS, McGwin G Jr, Uribe A, Friedman AW, Roseman JM, Fessler BJ, et al. Systemic lupus erythematosus in a multiethnic lupus cohort (LUMINA). XVII: predictors of self-reported health-related quality of life early in the disease course. Arthritis Rheum 2004;51: Strand V, Petri M, Kalunian K, Gordon C, Wallace DJ, Hobbs K, et al. Epratuzumab for patients with moderate to severe flaring SLE: health-related quality of life outcomes and corticosteroid use in the randomized controlled ALLEVIATE trials and extension study SL0006. Rheumatology (Oxford) 2014; 53: Jolly M, Pickard AS, Block JA, Kumar RB, Mikolaitis RA, Wilke CT, et al. Disease-specific patient reported outcome tools for systemic lupus erythematosus. Semin Arthritis Rheum 2012;42: McElhone K, Abbott J, Shelmerdine J, Bruce IN, Ahmad Y, Gordon C, et al. Development and validation of a diseasespecific health-related quality of life measure, the LupusQol, for adults with systemic lupus erythematosus. Arthritis Rheum 2007;57: Kaya A, Goker B, Cura ES, Tezcan ME, Tufan A, Mercan R, et al. Turkish LupusPRO: cross-cultural validation study for lupus. Clin Rheumatol 2014;33: Jolly M, Toloza S, Block J, Mikolaitis R, Kosinski M, Wallace D, et al. Spanish LupusPRO: cross-cultural validation study for lupus. Lupus 2013;22: Bourre-Tessier J, Clarke AE, Mikolaitis-Preuss RA, Kosinski M, Bernatsky S, Block JA, et al. Cross-cultural validation of a disease-specific patient-reported outcome measure for systemic lupus erythematosus in Canada. J Rheumatol 2013;40: Navarra SV, Tanangunan RM, Mikolaitis-Preuss RA, Kosinski M, Block JA, Jolly M. Cross-cultural validation of a diseasespecific patient-reported outcome measure for lupus in Philippines. Lupus 2013;22: Hochberg MC. Updating the American College of Rheumatology revised criteria for the classification of systemic lupus erythematosus [letter]. Arthritis Rheum 1997;40: Guillemin F, Bombardier C, Beaton D. Cross-cultural adaptation of health related quality of life measures: literature review and proposed guidelines. J Clin Epidemiol 1993;46: Mokkink LB, Terwee CB, Patrick DL, Alonso J, Stratford PW, Knol DL, et al. International consensus on taxonomy, terminology, and definitions of measurement properties for healthrelated patient-reported outcomes: results of the COSMIN study. J Clin Epidemol 2010;63: Petri M, Kim MY, Kalunian KC, Grossman J, Hahn BH, Sammaritano LR, et al, for the OC-SELENA Trial. Combined oral contraceptives in women with systemic lupus erythematosus. N Engl J Med 2005;353: Gladman D, Ginzler E, Goldsmith C, Fortin P, Liant M, Urowitz M, et al. The development and initial validation of the Systemic Lupus International Collaborating Clinics/American College of Rheumatology Damage Index for systemic lupus erythematosus. Arthritis Rheum 1996;39: Hu LT, Bentler PM. Cutoff criteria for fit indices in covariance structure analysis: conventional criteria versus new alternatives. Struct Equ Modeling 1999;6: Jackson DL, Gillaspy JA, Purc-Stephenson R. Reporting practices in confirmatory factor analysis: an overview and some recommendations. Psychol Methods 2009;14: MacCallum RC, Browne MW, Sugawara HM. Power analysis and determination of sample size for covariance structure modeling. Psychol Methods 1996;1: Steinberg L, Thissen D. Uses of item response theory and the testlet concept in the measurement of psychopathology. Psychol Methods 1996;1: Strand V, Gladman D, Isenberg D, Petri M, Smolen J, Tugwell P. Endpoints: consensus recommendations from OMERACT IV: outcome measures in rheumatology. Lupus 2000;9: Gordon C, Isenberg D, Lerstrom K, Norton Y, Nikai E, Pushparajah DS, et al. The substantial burden of systemic lupus erythematosus on the productivity and careers of patients: a European patient-driven online survey. Rheumatology (Oxford) 2013;52:

8 304 Mok et al 28. Jolly M, Utset TO. Can disease specific measures for systemic lupus erythematosus predict patients health related quality of life? Lupus 2004;13: Kuriya B, Gladman DD, Ibanez D, Urowitz MB. Quality of life over time in patients with systemic lupus erythematosus. Arthritis Rheum 2008;59: Aggarwal R, Wilke CT, Pickard AS, Vats V, Mikolaitis R, Fogg L, et al. Psychometric properties of the EuroQol-5D and Short Form-6D in patients with systemic lupus erythematosus. J Rheumatol 2009;36: Gallop K, Nixon A, Swinburn P, Sterling KL, Naegeli AN, Silk ME. Development of a conceptual model of health-related quality of life for systemic lupus erythematosus from the patient s perspective. Lupus 2012;21: Touma Z, Urowitz MB, Gladman DD. Outcome measures in systemic lupus erythematosus. Indian J Rheumatol 2013;8 Suppl 1:S46 S Jolly M, Kosinski M, Toloza S, Block JA, Mikolaitis RA, Duran-Barragan S, et al. Equivalence of various language versions of lupus specific patient reported outcomes measure (LupusPRO) [abstract]. Arthritis Rheum 2012;Suppl 10:S Jolly M, Cornejo J, Mikolaitis RA, Block JA. LupusPRO and responsiveness to changes in health status and disease activity over time [abstract]. Arthritis Rheum 2011;Suppl 10:S898.